Can I tell which version of newlib I have?
Ray Hurst
rhurst2@cox.net
Wed Apr 25 01:21:00 GMT 2007
Dave Korn wrote:
> On 25 April 2007 00:19, Ray Hurst wrote:
>
>> Brian Dessent wrote:
>
>>> In the case of Cygwin, the C library is provided by Cygwin, in the form
>>> of cygwin1.dll. Cygwin relies on newlib to implement some things, but
>>> malloc is not one of them.
>
>> Technically you are correct. gcc does not care. However, gcc is
>> typically used to invoke the linker which does care where the C library
>> is. Most command lines that use gcc to compile and link do not specify
>> where the C library is as gcc or the linker knows where it is.
>>
>> What I am asking is how do these programs find the C library on a cygwin
>> system running on windows? Specifically. I am looking for the library
>> that contains the malloc function but I would like the general info also.
>
> Take a look at the output from "gcc -v" when compiling and linking a "Hello
> World":
>
> --------------------------------<snip!>--------------------------------
> Reading specs from /usr/lib/gcc/i686-pc-cygwin/3.4.4/specs
> Configured with: /usr/build/package/orig/test.respin/gcc-3.4.4-3/configure
> --verbose --prefix=/usr --exec-prefix=/usr --sysconfdir=/etc --libdir=/usr/lib
> --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info
> --enable-languages=c,ada,c++,d,f77,pascal,java,objc --enable-nls
> --without-included-gettext --enable-version-specific-runtime-libs --without-x
> --enable-libgcj --disable-java-awt --with-system-zlib --enable-interpreter
> --disable-libgcj-debug --enable-threads=posix --enable-java-gc=boehm
> --disable-win32-registry --enable-sjlj-exceptions
> --enable-hash-synchronization --enable-libstdcxx-debug
> Thread model: posix
> gcc version 3.4.4 (cygming special, gdc 0.12, using dmd 0.125)
> /usr/lib/gcc/i686-pc-cygwin/3.4.4/cc1.exe -quiet -v -D__CYGWIN32__
> -D__CYGWIN__ -Dunix -D__unix__ -D__unix -idirafter
> /usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../../i686-pc-cygwin/lib/../include/w3
> 2api -idirafter
> /usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../../i686-pc-cygwin/lib/../../include
> /w32api hello.c -quiet -dumpbase hello.c -mtune=pentiumpro -auxbase hello
> -version -o /win/c/DOCUME~1/dk/LOCALS~1/Temp/ccccycor.s
> #include "..." search starts here:
> #include <...> search starts here:
> /usr/local/include
> /usr/lib/gcc/i686-pc-cygwin/3.4.4/include
> /usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../../i686-pc-cygwin/include
> /usr/include
>
> /usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../../i686-pc-cygwin/lib/../include/w3
> 2api
>
> /usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../../i686-pc-cygwin/lib/../../include
> /w32api
> End of search list.
> GNU C version 3.4.4 (cygming special, gdc 0.12, using dmd 0.125)
> (i686-pc-cygwin)
> compiled by GNU C version 3.4.4 (cygming special, gdc 0.12, using dmd
> 0.125).
> GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
> /usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../../i686-pc-cygwin/bin/as.exe -o
> /win/c/DOCUME~1/dk/LOCALS~1/Temp/cc8gFoYM.o
> /win/c/DOCUME~1/dk/LOCALS~1/Temp/ccccycor.s
> --------------------------------<snip!>--------------------------------
>
> This is the interesting bit: the linker commandline.
>
> --------------------------------<snip!>--------------------------------
> /usr/lib/gcc/i686-pc-cygwin/3.4.4/collect2.exe -Bdynamic
> --dll-search-prefix=cyg -o hello.exe
> /usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../../i686-pc-cygwin/lib/crt0.o
> -L/usr/lib/gcc/i686-pc-cygwin/3.4.4 -L/usr/lib/gcc/i686-pc-cygwin/3.4.4
> -L/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../../i686-pc-cygwin/lib
> -L/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../..
> /win/c/DOCUME~1/dk/LOCALS~1/Temp/cc8gFoYM.o -lgcc -lcygwin -luser32 -lkernel32
> -ladvapi32 -lshell32 -lgcc
> --------------------------------<snip!>--------------------------------
>
> Gcc just supplies the relevant search paths for the libraries. The standard
> system libraries to link against are this bit:
>
> --------------------------------<snip!>--------------------------------
> -lgcc -lcygwin -luser32 -lkernel32 -ladvapi32 -lshell32 -lgcc
> --------------------------------<snip!>--------------------------------
>
> Where do they come from? Look at the start of the output again:
>
> --------------------------------<snip!>--------------------------------
> Reading specs from /usr/lib/gcc/i686-pc-cygwin/3.4.4/specs
> --------------------------------<snip!>--------------------------------
>
> That's the specs file. Specs are an internal set of options that gcc uses
> to specify how to parse a commandline and pass options on to the substages
> (preprocessing, compilation, assembly, linking) of the whole process: see
> section 3.15, "Specifying subprocesses and the switches to pass to them" in
> "info gcc" for more detail. The stuff it contains is actually built-in to the
> gcc compile driver as well. Look at the output of "gcc --help":
>
> --------------------------------<snip!>--------------------------------
> /tmp $ gcc --help
> Usage: gcc [options] file...
> Options:
> -pass-exit-codes Exit with highest error code from a phase
> --help Display this information
> --target-help Display target specific command line options
> (Use '-v --help' to display command line options of sub-processes)
> -dumpspecs Display all of the built in spec strings
> -dumpversion Display the version of the compiler
> -dumpmachine Display the compiler's target processor
> -print-search-dirs Display the directories in the compiler's search
> path
>
> -print-libgcc-file-name Display the name of the compiler's companion
> library
> -print-file-name=<lib> Display the full path to library <lib>
> -print-prog-name=<prog> Display the full path to compiler component <prog>
> -print-multi-directory Display the root directory for versions of libgcc
> -print-multi-lib Display the mapping between command line options
> and
> multiple library search directories
> -print-multi-os-directory Display the relative path to OS libraries
> -Wa,<options> Pass comma-separated <options> on to the assembler
> -Wp,<options> Pass comma-separated <options> on to the
> preprocessor
>
> -Wl,<options> Pass comma-separated <options> on to the linker
> -Xassembler <arg> Pass <arg> on to the assembler
> -Xpreprocessor <arg> Pass <arg> on to the preprocessor
> -Xlinker <arg> Pass <arg> on to the linker
> -save-temps Do not delete intermediate files
> -pipe Use pipes rather than intermediate files
> -time Time the execution of each subprocess
> -specs=<file> Override built-in specs with the contents of <file>
> -std=<standard> Assume that the input sources are for <standard>
> -B <directory> Add <directory> to the compiler's search paths
> -b <machine> Run gcc for target <machine>, if installed
> -V <version> Run gcc version number <version>, if installed
> -v Display the programs invoked by the compiler
> -### Like -v but options quoted and commands not
> executed
> -E Preprocess only; do not compile, assemble or link
> -S Compile only; do not assemble or link
> -c Compile and assemble, but do not link
> -o <file> Place the output into <file>
> -x <language> Specify the language of the following input files
> Permissible languages include: c c++ assembler none
> 'none' means revert to the default behavior of
> guessing the language based on the file's extension
>
> Options starting with -g, -f, -m, -O, -W, or --param are automatically
> passed on to the various sub-processes invoked by gcc. In order to pass
> other options on to these processes the -W<letter> options must be used.
>
> For bug reporting instructions, please see:
> <URL:http://cygwin.com/problems.html>.
> @_______. .
> ( /"\
> ||--||(___)
> '" '"'---'
> /tmp $
> --------------------------------<snip!>--------------------------------
>
> It's the various -print* and -dump* ones that are interest. Take a look at
> the specs:
>
> --------------------------------<snip!>--------------------------------
> /tmp $ gcc -dumpspecs 2>&1 | tee -a gcc.log
> *asm:
>
>
> *asm_debug:
> %{gdwarf-2*:--gdwarf2}%{!gdwarf-2*:%{g*:--gstabs}}
>
> *asm_final:
>
>
> *asm_options:
> %a %Y %{c:%W{o*}%{!o*:-o %w%b%O}}%{!c:-o %d%w%u%O}
>
> *invoke_as:
> %{!S:-o %|.s |
> as %(asm_options) %m.s %A }
>
> *cpp:
> %(cpp_cpu) %{posix:-D_POSIX_SOURCE} %{mno-win32:%{mno-cygwin: %emno-cygwin
> and mno-win32 are not compatible}} %{mno-cygwin:-D__MSVCRT__ -D__MINGW32__
> %{!ansi:%{mthreads:-D_MT}}} %{!mno-cygwin:-D__CYGWIN32__ -D__CYGWIN__
> %{!ansi:-Dunix} -D__unix__ -D__unix } %{mwin32|mno-cygwin:-DWIN32 -D_WIN32
> -D__WIN32 -D__WIN32__ %{!ansi:-DWINNT}}
> %{!nostdinc:%{!mno-win32|mno-cygwin:-idirafter ../include/w32api%s -idirafter
> ../../include/w32api%s}}
>
> *cpp_options:
> %(cpp_unique_options) %1 %{m*} %{std*&ansi&trigraphs} %{W*&pedantic*} %{w}
> %{f*} %{g*:%{!g0:%{!fno-working-directory:-fworking-directory}}} %{O*}
> %{undef}
>
> *cpp_debug_options:
> %{d*}
>
> *cpp_unique_options:
> %{C|CC:%{!E:%eGCC does not support -C or -CC without -E}} %{!Q:-quiet}
> %{nostdinc*} %{C} %{CC} %{v} %{I*} %{P} %I %{MD:-MD %{!o:%b.d}%{o*:%.d%*}}
> %{MMD:-MMD %{!o:%b.d}%{o*:%.d%*}} %{M} %{MM} %{MF*} %{MG} %{MP} %{MQ*} %{MT*}
> %{!E:%{!M:%{!MM:%{MD|MMD:%{o*:-MQ %*}}}}} %{remap} %{g3:-dD} %{H} %C
> %{D*&U*&A*} %{i*} %Z %i %{E|M|MM:%W{o*}}
>
> *trad_capable_cpp:
> cc1 -E %{traditional|ftraditional|traditional-cpp:-traditional-cpp}
>
> *cc1:
> %(cc1_cpu)
>
> *cc1_options:
> %{pg:%{fomit-frame-pointer:%e-pg and -fomit-frame-pointer are incompatible}}
> %1 %{!Q:-quiet} -dumpbase %B %{d*} %{m*} %{a*} %{c|S:%{o*:-auxbase-strip
> %*}%{!o*:-auxbase %b}}%{!c:%{!S:-auxbase %b}} %{g*} %{O*} %{W*&pedantic*} %{w}
> %{std*&ansi&trigraphs} %{v:-version} %{pg:-p} %{p} %{f*} %{undef}
> %{Qn:-fno-ident} %{--help:--help} %{--target-help:--target-help}
> %{!fsyntax-only:%{S:%W{o*}%{!o*:-o %b.s}}} %{fsyntax-only:-o %j} %{-param*}
>
> *cc1plus:
>
>
> *link_gcc_c_sequence:
> %G %L %G
>
> *endfile:
>
>
> *link:
> %{mwindows:--subsystem windows} %{mconsole:--subsystem console}
> %{shared: %{mdll: %eshared and mdll are not compatible}} %{shared: --shared}
> %{mdll:--dll} %{static:-Bstatic} %{!static:-Bdynamic} %{shared|mdll: -e
> %{mno-cygwin:_DllMainCRTStartup@12} %{!mno-cygwin:__cygwin_dll_entry@12}}
> %{!mno-cygwin:--dll-search-prefix=cyg}
>
> *lib:
> %{pg:-lgmon} %{!mno-cygwin:-lcygwin}
> %{mno-cygwin:%{mthreads:-lmingwthrd} -lmingw32} %{mwindows:-lgdi32
> -lcomdlg32} -luser32 -lkernel32 -ladvapi32 -lshell32
>
> *libgcc:
> %{mno-cygwin: %{mthreads:-lmingwthrd} -lmingw32} -lgcc
> %{mno-cygwin:-lmoldname -lmingwex -lmsvcrt}
>
> *startfile:
> %{shared|mdll: %{mno-cygwin:dllcrt2%O%s}} %{!shared: %{!mdll:
> %{!mno-cygwin:crt0%O%s} %{mno-cygwin:crt2%O%s} %{pg:gcrt0%O%s}}}
>
> *switches_need_spaces:
>
>
> *cross_compile:
> 0
>
> *version:
> 3.4.4
>
> *multilib:
> . ;
>
> *multilib_defaults:
>
>
> *multilib_extra:
>
>
> *multilib_matches:
>
>
> *multilib_exclusions:
>
>
> *multilib_options:
>
>
> *linker:
> collect2
>
> *link_libgcc:
> %D
>
> *md_exec_prefix:
>
>
> *md_startfile_prefix:
>
>
> *md_startfile_prefix_1:
>
>
> *startfile_prefix_spec:
>
>
> *sysroot_suffix_spec:
>
>
> *sysroot_hdrs_suffix_spec:
>
>
> *cc1_cpu:
> %{!mtune*: %{m386:mtune=i386 %n`-m386' is deprecated. Use `-march=i386' or
> `-mtune=i386' instead.
> } %{m486:-mtune=i486 %n`-m486' is deprecated. Use `-march=i486' or
> `-mtune=i486' instead.
> } %{mpentium:-mtune=pentium %n`-mpentium' is deprecated. Use `-march=pentium'
> or `-mtune=pentium' instead.
> } %{mpentiumpro:-mtune=pentiumpro %n`-mpentiumpro' is deprecated. Use
> `-march=pentiumpro' or `-mtune=pentiumpro' instead.
> } %{mcpu=*:-mtune=%* %n`-mcpu=' is deprecated. Use `-mtune=' or '-march='
> instead.
> }} %<mcpu=* %{mpni:-msse3 %n`-mpni' is deprecated. Use `-msse3' instead.
> } %{mno-pni:-mno-sse3 %n`-mno-pni' is deprecated. Use `-mno-sse3' instead.
> } %{mintel-syntax:-masm=intel %n`-mintel-syntax' is deprecated. Use
> `-masm=intel' instead.
> } %{mno-intel-syntax:-masm=att %n`-mno-intel-syntax' is deprecated. Use
> `-masm=att' instead.
> }
>
> *mingw_include_path:
> i686-pc-cygwin
>
> *link_command:
> %{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S: %(linker) %l %{pie:-pie} %X
> %{o*} %{A} %{d} %{e*} %{m} %{N} %{n} %{r} %{s} %{t} %{u*} %{x} %{z} %{Z}
> %{!A:%{!nostdlib:%{!nostartfiles:%S}}} %{static:} %{L*} %(link_libgcc) %o
> %{fprofile-arcs|fprofile-generate:-lgcov}
> %{!nostdlib:%{!nodefaultlibs:%(link_gcc_c_sequence)}}
> %{!A:%{!nostdlib:%{!nostartfiles:%E}}} %{T*} }}}}}}
> --------------------------------<snip!>--------------------------------
>
>
> This is the pertinent one:
>
> --------------------------------<snip!>--------------------------------
> *lib:
> %{pg:-lgmon} %{!mno-cygwin:-lcygwin}
> %{mno-cygwin:%{mthreads:-lmingwthrd} -lmingw32} %{mwindows:-lgdi32
> -lcomdlg32} -luser32 -lkernel32 -ladvapi32 -lshell32
> --------------------------------<snip!>--------------------------------
>
> You can look up the docs I mentioned above to see how it works, but I guess
> you can probably see that it's the sort of thing that might be responsible for
> causing
>
> -lgcc -lcygwin -luser32 -lkernel32 -ladvapi32 -lshell32 -lgcc
>
> to appear. (The compiler prefixes and suffixes the list with -lgcc twice
> automatically).
>
> So, now you know where the linker is told to search, and what for. Most of
> this is specified when the compiler is configured for a cygwin system. If you
> wanted to play with it, you could make a copy of the default specs file, hack
> it about, and get gcc to make use of it by the -specs=<file> commandline
> option.
>
> The final piece of the jigsaw? You know it links against cygwin1.dll, you
> know it searchs in /usr/lib, so let's take a look at the symbols defined
> there:
>
> /tmp $ nm /usr/lib/libcygwin.a | grep '__imp__'
>
> and there, amongst many many others, you will see:
>
> 00000000 I __imp__lroundf
> 00000000 I __imp__lsearch
> 00000000 I __imp__lutimes
> 00000000 I __imp__mallinfo
> 00000000 I __imp__malloc
> 00000000 I __imp__malloc_stats
> 00000000 I __imp__malloc_trim
> 00000000 I __imp__malloc_usable_size
> 00000000 I __imp__mallopt
> 00000000 I __imp__matherr
> 00000000 I __imp__mblen
> 00000000 I __imp__mbrlen
> 00000000 I __imp__mbrtowc
> 00000000 I __imp__mbsinit
>
> so, it gets malloc imported from cygwin1.dll. There is no way to know from
> the sight of the symbol whether it was originally from newlib or whether
> cygwin supplied its own; that's the point at which you have to start checking
> the sources to know. (Though as Brian says, it's from cygwin.)
>
>
> cheers,
> DaveK
Thanks. This is the stuff I was looking for.
Ray
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